Lens blocking device



NO 1953 D. P. BERNHEIM ET AL ,660,

' LENS BLOCKING DEVICE 7 Filed Aug. 7, 1948 v 5 Sheets-Sheet l no INVENTORS 471g 1 DAN\EL. P. BERNHEHW cARL e smvERBaRe ATTORNEY NOV. 1953 D. P. BERNHEIM ET AL 2,660,011

LENS BLOCKING DEVICE Filed Aug. '7, 1948 5 Sheets-Sheet 2 $1M] l v fig 1 1 INVENTORS DANIEL P. aemmem emu. e. swanaavze ATTORNEY 2 1953 D. P. BERNHEIM ET AL ,0 1

LENS BLOCKING DEVICE Filed Aug. 7, 1948 5 Sheets-Sheet 3 ATTORNEY D. P. BERNHEIM ET AL Nov. 24, 1953 LENS BLOCKING DEVICE 5 Sheets-Sheet 4 Filed Aug. 7, 1948 fig 16 INVENTORS DAN\E.L. P. BERNHFJM CARL. G. S\LVEKBERG BY ATTORNEY V 1953 D. P. BERNHEIMT ET AL 2,660,011

LENS BLOCKING DEVICE I Filed Aug. 7, 1948 5 Shets-Sheet 5 fig 13 fig 15 IN VEN TORS DAN\EL P. BERNHBM CARL G s\ w ERBERG ATTORN EV Patented Nov. 24, 1953 ATENT "OFFICE Silverberg, Sturbridge, 'Mass :Gompany,

American Optical assignors to 'snuthbridge,

1Mass,, ayoluntary associationofMassachusetts ApplicationAugus't 7, 1948, :SerialtNo. 43,066

.16 .Claims. 1

This invention :relates to improvements in blocking devices and has particular-reference to improved :means and :method of blocking lenses. One of the :principal objects of the invention is to provide improved :means and method of blocking semi-finished lens blanks whereby the positional factors of the finished prescriptive power which the lensiis to possess may be located prior to the blocking and the said 'lens blank blocked while helol in said located position.

Another :object of the invention is :to :provide improved means .and :method of blocking lenses whereby the prism and cylinder axes and extent of said prism may be located --prior to blocking the semi-finished lens blank and the said lens blankblockedwhile held in said position.

Another object is to provide improved sighting and gripping meansforsemi-fihished lens blanks whereby the optical characteristics which the finishedlens is to possessmay be predetermined and the said lens blank held 'by said gripping means in such a manner as-to'retain-its position with respect to its prescriptive characteristics, whereby it may betransferred bya slight vertical movement into alignment with and be-securedto a lens block while held-in said position.

Another objectis to provide a "device having means for supporting a lens blank, means gfor supporting :a lens block on a vertical axis with said lens blank, an upright having sighting and gripping meansvertically'movableinto and out of adjacent relation wit-hthe'lens blank and adapted to position said lens (blank with respect to said lens block.

Another object is ,to provide a devioe'having means for positioning a lens blank with respect to the prescriptive characteristics which the finished lens is to possess, means'for gripping and moving "thelensblahk vertically while held in said position, and .meansjor returning the blank and attaching said Lblank ltola'jens block at .substan'tially .thesame general location whereit was originally positioned and gripped.

Another object is the provision of means tor preliminary attaching ad-hesives 'in the .form .of pellets to blocksso that theblocks can be .positioned in the blocking device with the adhesives firmly attached.

Another object is the provision of alfurnace having suitahlaautomatic timecnntrol for simultaneously attachingapluralityof adhesive pellets .to a plurality-of blocks.

Another nbiect is the l provision 0f a movable heating element positioned :-f or insertion :between a lensblankand alens-block carryingan adhesive to simultaneously heat the adjacent surfaces thereof before securing .the blank to the block.

Another object is the provisionof an electronic timing {device forygoverning the heating A cycle for theilens-blank andlens block and controlling electrical:mechanism--for automatically removing the heating element ,from its position between the lens blank :and lens block and automatically causing the means carrying the lens blank to deposit the blank mount-he lens --blockand'a-dhe sive carried thereby.

The-invention {also consists =of'new and original features:of construction and combination ofparts hereinafter set forth and =claimed. Although-the novel features are shown and described and are pointed-out in the .:claims, the-present invention will be moreclearly understood and the-advantages :t-herieof fully realized from the followin line 2--2 of Fig. "1 showing the sighting and gripping means foraligning a lens blank;

Fig. 3 is a plan view of :said device partly in section with the sighting means removed toshow the heating element and associated parts;

Fig. 4 "isan enlarged fragmentary front elevational *view showing the heating element'in position for heating the lens blank and the lens block;

Fig. '5is an enlarged 'fragmentaryfront elevational view showingthe method of securing the lens blank'to thelens block;

Fig. '6 is a fragmentary sectional view taken on line '6--6 vof Fig. 1 showing the means for con oll ng the position Qfthe lens blank upportingLtablQ; 1

Fig. "7 is a sectional view showing details ofthe construction ,of the, lens block with ,a lens blank attache d .jthereto;

lEig. .8,is.: a sectional .view taken through. a .;por tion .nf :the supporting .bracket and illustrating particularly ,the spring detent mechanism for retaining thesigh ing d vicein raised posi i nli' g. .9 is .a sectional ,view vshowing the means for locating .thelens supporting-pins in-the prism adjusting device;

fig. :10 is.a front.elevation-illustratinga modifiedwty'peof .lens supp r ing pin;

Figllil isa fragmentarysectional view-showing a ,modi-fied .form of prism adjustment means.

Fig. 12 is a bottom plan view of a pitch pellet used as the adhesive for securing a lens blank to alens block;

Fig. 13 is a sectional view of the pitch pellet taken on line l3 3 of Fig. 12;

Fig. 14 is a front elevation of the furnace used for the preliminary attachment of the adhesive pellets to the lens blocks;

Fig. 15 is an enlarged sectional view taken on line 15-45 of Fig. 14; and

Fig. 16 is a schematic wiring diagram of the electronic control for the heating mechanism.

When blocking a lens for the forming of the final prescriptive surface on said lens it is of extreme importance that the said lens be located in properly cen ered position, and in instances wherein the said lens is to have a cylinder and prismatic correction embodied therein it is also of extreme importance that the axis of the cylinder and prism be located in the proper meridian and that the power thereof be accurately controlled.

An important feature of the present invention, therefore, is the provision of improved means and method whereby all of the positional and prescriptive characteristics which the resultant lens is to possess may be accurately determined prior to the final securing of the lens blank to the lens block so that the said lens blank will be held in proper position in the abrading machine 7 employed to complete the final prescriptive surface on said blank.

A unique feature of the present device and method is that it eliminates all guesswork and insures that the accurate optical characteristics are being introduced during the final abrading of the prescriptive surface on the lens blank.

Although means and metho s have been employed in the past for determining all the prescr ptive com onents of a lens rior to the final positioning of the lens blank with respect to the lens block, it has been very difficult to provide suitable means for efficiently securing the lens blank to the lens block. One of the most s tisfactory prior art devices was the type employing a pitch pot or kettle supported for positioning in alignment with the lens block to permit the flow of molten pit h from the kettle onto said lens block, the pitch having been previously rendered molten by heating means associated with the kettle. This process, is however, slow and messy and requires excessive handling of the lens blank by parts of the machine required to transfer the lens blank from sighting position to another section of the machine for securement to the lens block. This extra movement introduces an additional disadvantageous factor in that there is a possibility that the lens blank may be accidentally shifted from its position as initially located during the transfer to the lens block and thus be consequently inaccurately finished.

The present invention improves upon prior art device by providing a removable table for locating the lens blank adjacent the sighting means, the table being provided with improved means for positioning the lens blank with respect to the amount of prism to be provided, and providing means for positioning a heating element between the lens blank and the lens block to which the blank is to be secured to simultaneously heat the blank and the block, for fixedly securing the lens blank to the lens block, the block havin previously had an adhesive in the nature of a solid secured thereto by means of a furnace which is adapted to simultaneously secure a plurality of adhesive pellets to a corresponding number of lens blocks, the furnace having means for projecting radiant heat onto the blocks and pellets for a predetermined length of time in accordance with the setting of a timing device associated with the device. With this construction there is also provided means for raising the lens blank vertically from the table and lowering the blank into contacting position with the lens block, the entire line of movement of the lens blank being always in a direction perpendicular to the sur face of the lens blank supporting table.

This eliminates excessive movement of the lens blank after being positioned by the sighting device, and also eliminates the use of a kettle carrying a liquid adhesive, together with the acces sories necessary for confining the liquid adhesive to the desired surfaces to be adhered, consequently resulting in an accurate positioning of the lens blank upon the lens block in a neat and eificient manner.

A further improvement resides in the provision of an electronic timing device for controlling the length of time the heating element is operated to heat the adjacent surfaces of the lens blank and the block carrying the previously aiiixed adhesive. This timing control prevents the possi bility of overheating which may have the dis asterous consequences of craking the lens blank or burning the adhesive, or if the heating cycle is too short the lens blank may not be securely attached to the block.

Referring more particularly to the drawings wherein like characters of reference designate like parts throughout the several views, the device embodying the invention comprises a hollow base 1 having spaced parallel transverse supports 2 and S thereon. Extending upwardly adjacent the rear ends of the supports 2 and 3 is a hollow upright (Fig. 2) having a web 5 in the upper portion thereof adapted to carry a forwardly and upwardly extending supporting bracket 6, the bracket being fixedly secured to the web 5 by means such as screws or bolts 7.

Located in spanning relation to the forward portions of the spaced supports 2 and 3 is a movable table 8 provided on the underside thereof with a plurality of removable metal pads 9, (Figs. 2 and 6), each of which pads is adapted to make end to end contact with a corresponding aligned removable metal pad Ill, the pads ii! being located in the upper surfaces of the supports 2 and 3 and in the upper surface of a protruding portion H of the front wall of the upright d. The adjoining surfaces of the pads 9 and it are machined so that the upper surface of the table 8 will be located in a perfectly horizontal plane, it being possible to adjust this plane by grinding the ends of one or more of the pads 9 and I9. Locking pins I2 are fixedly located in the upper surfaces of the supports 2 and 3 and are adapted to removably engage bushings I 3 located in the under side of the table 8, and serve to hold the table stationary. The table 8, supports 2 and 3, and upright portion I are provided with vertical openings M concentric with the inner ends of pads 9 and It and bushings I3 so that they may be easily knocked out for repair or replacement if desired.

Manually operative means is provided for moving the table 8 and includes a vertical shaft I5 (Fig. 6) rotatably mounted throughout the major portion of its length in a fixed bushing IT in the support 3 and having its upper end fixedly secured ineariheright rear coTnerofrtl-retfiifilmflsandheld in rsaid *flxed position :;by a set screw 12155 on dike. Spaced :bushings lzlfltare fixedlyllocaimdzin the Ifront land :rear :ends ;:of :the support :3 sand serve to rotatably support a :itr-ans'verse. shafit 213,

the iforward end of whichcarr'ies a hub 20 :se-

cured thereon by a pin ZIJtheFrearCendnf shaft 21:9 ihav-ing awas'her .22 isecured thereon rhyeaapin 2235forretainingztheshait:Hi' imposition. handle as is .Lsecured to :t-heZ-hub 512i and .:serves :to irritate :the shaft 19., the :shaft 9 :being :proyided radiarcenttthepointtof contact rzby theioivereend ofrthe vertical shaft N with accamIpoI-tionIZrS the cam portion. a being adaptedtto rralisetthsshait 55 when .the handle-241s: operated to'Jmtate shaft 7: subsequently will lift the :table 1:8 roff theigpins as indicated in :d'otted .:outline:in @ig. 2'5, perm-itizingithe :table to be swung to neside .aieolrt'ihe axis hi the shaft I15 Ito .ra p'o'sition zas Lin Fig.3. .The verticalshafti'l5'dsprovided with a longitudinal :bore 2256 ".to permit the scam portion Z21 5 of :tthe 'sl'iaft 9 to Zbe lubricated, 1311118 I assuringeasy operation of the device, and-thetable 85 is provided at the corner diagonally :across ."from :fs'haft 15 with a short "extension aorth'a-ndle i portion 2'5 to be graspedihy the QDeratorIfnr-ease .in'moving the table.

"The table it has arota'tably snountedionzthe up- ."per sunface theredf a "disc member 128 :having a fcentrral'lyll'ocated vertical opening 29 :in'whi'ch is F ffixe'd'ly secured a translucent member :31], 'ith'e opening 219 'rbeingzin" vertical alignment with scon centric openings 3] and .32 in ttheitable it and ibase 1 "respectively. Thus, ll-ight'emanat-ing ffrom base 1 "as by a sochetat :andtzbraeket r35 roan :be seen through thetranslucentlightdifiusingmem her 'tt. (Fig.2), the lightheingienergizeditby:any suitable sourceof current.

ill-"retainingring .3 6 its securedf to theuppersurface or "the table It "by means ssuch .eas. screws 31,

the disc 28 "being "of such hiameter as "to isnugly reside within the opening "in'the firing-r3 GI'YBJIIGLTD- ta'te therein. Fixedly "secured *to the upp'errsurface or the disc 26 is 'aloe-veled ringlmemheritfi i "having a groove or channel ed "(Fig. 9') form ed'in the periphery thereof, "the member -38 ibeing'sre movahly mounted on the disc ZB by means of pins '4 the pins '4 I being fixedly mounted in ithe r'disc tit-and adaptedito .comate with vertical openings 5 edge of theimemberizefl 'inesuch almanner st-hat the channel'zsa cuts-into the-side walls nfrthe openings et to provide "a passageway into :said openings. :Prism regulating pins i3 :of varying lengths are adapted tuber-inserted.intotheopenjngs t-B. 'Thepins'larepprovided'with aicireum-fer ential groove 4% in which a circular springiclip or ring 5 55, :positionedinthe :Channe1-r3%9,:is adapt- ;ed to removahly' retain the :pins. in ike openings. Thus, the pins it may he lifted-:upwardly-iagainst the tension eXer-ted'by -t'heclip'orring ton-be 1 replaced or the like, With':the"-replaoement=pin inserted into the opening at =andeforced-idownwardly against the pressure exerted the clip or :ring 415 to become .firmly seated in a manner 192$"f'ShOWDLiI1 Fig. 9. 'l hewupper endtof.eaeh zpin M iis .providediwitha .zballfbeafingdzip "'46, :or may have a conical shape having a short extension 4'! .satrth'e apex asrshownfin Fig. 10, .zalensiblank 5:0 tobbe ab'lncked being adapted to :berested :upon sthe portionsiw .or 4liof'thejpins'43.

".The tidisc 2B is provided with a plurality pf .10- cationilines A8 which cooperatively function with a tdegree scale 49 marked on the:retaining.;ring 13'6. Thecamountof the'prism'which'isito be;introduced ainrthe lens'blank zdflgwhich lens blank is Ztbeing-supported by the ends of the pins 143, )is determined by positioning pins 43 of the :desired-rcontitolledilengthsiin the openings 46 1 in the memberitfi. .jiByi inserting pins .of varying lengths .it' willi he seenithat "the -lens blank 'Will :repose at varying angles, :and by this means various amounts ofprismimaylbe introduced in thelens. Theilocationlines 14:8 and degree scale 49 are "for the purpose :of .locating :the'lo'lank in the proper meridianaccording toithe cylinder axis or prism of prism may'be introduced as well as accurate centering.

the lens blank has been positioned, as

stated above, a plurality o'fnontact members-:5! are moved directly into "engagement with the upper surface of the lens blanket. The contact members 5 l :asw'shownin Fig. 2, are independently .urgedtoward theilens 'lelank 50 by means of backing springsifilitvhich engage each of the contact members 5i atone end thereof, as indicated at 53,:and .atthe-opposite :ends engage "a split washer M. The Washer-5'4 'iSfDlllflfid of two semi-circular shaped members which are adapted to be .l'ocatedz'inza circumferential groove in the sight ing device ibodymember by means of a spring clip Wire 5'15, ithe supper ends of the hacking springs 52 being adapted to engage the lower surface or the washer .5 3. The body member 55 .ofithesighting device is vertically movable interna'llyrof ahousing'tcarried'by the supporting bracket i6 and is provided with a plurality of longitudinal' grooves 51., as shown in Fig. 2. The -contact members '5'! "and backing springs 52 are positioned within these grooves 53 with sufficient clearance so 'that'the body membersa and attached parts arefreetto reciprocate as a unit in the .a'housing 5'8. The "longitudinal grooves 57 3 3; temninateiatitheir lower-ends 'in-sh'ouldered edges 59 andcommuni'oate with a plurality of openin'gs in which the reduced portions of the contact 'membersti are 'sli'dably mounted. The members "51 areeaoh provided with a shouldered portion '6! which is adapted to 'engage'theshouldered edge 59 of the grooves 57 and limit .the downward movement of said members 5i under the reaction of "the hacking springs 52. "The lower end o'fthe body member 55 is provided with a pluralityof transversely extending openings .fifla directly intercepting the openings iii! in which the reducedportions of the contact incinhers .54 are :slidaloly mounted. Each of said latter openings is adapted touteceive the shank ofa knurled clam-pscrew 152 (Fig. l) :theends of theshank being adapted to directly or indirectly engage the contaot'members 5i Whenthe clamp screws 162 were operated by any suitable method -Whichnrray be'usedifor lcckingthe contact members against longitudinal 'movement in the openings to.

The clamp screws G2 are also indirectly connected-by. means not shown with a plurality of downwardly extending spring fingers t3, which fingers are rigidly attached adjacent their upper ends to a ring member be pressed or otherwise fixedly secured about the body member 55 near the lower end thereof and have their lower ends provided with means such as heat resistant rubber tubing or other suitable means forming cushion grips $5 for engaging the edge of and for gripping the lens blank so. The clamp screws 62 and spring fingers 5 are constructed and function the same manner as shown in Patent No. 2,253,95 issued August 26, 1941 to Lloyd /V. Goddu. It is believed sufiicient to state that in the present invention a manually operable handle 56 (Fig. i) protrudes from the casing 67 and is adapted to be moved transversely in a slotted opening in the casing ii? to rotate a cam mechanism, which earn mechanism controls the inward and outward oscillating movement of the spring fingers 53. When the clamp screws 62 are loosened the handle Er: may be moved within the confines of the slotted opening whereby the grips 65 of th spring fingers 63 are permitted to engage the edge of the lens blank 59, gripping the said blank through the inherent resiliency of the fingers, and are held in gripping relation with the edge of the blank by tightening the clamp screws 62, which tightening operation simultaneously locks the contact members 5! against longitudinal movement in the openings til.

The body member 55 is provided, as shown in Fig. 2, with a hollow bore in which is extended a sighting tube 6%. This tube is secured to a cap member 55 and has a washer it located adjacent the upper end thereof, the washer being provided with a restricted opening H centrally thereof. The cap member 58 is similarly provided with a restricted opening E2 in axial alignment with the opening "H and has a tapered portion 13 internally of the housing 53, the taper of the portion 73 being such that tightening of the screws It automatically cams the cap member $9 in a direction inwardly of the housing and forces the flange portion E5 of said cap member 69 into binding relation with the upper edge surface of the housing 58. The lower end of the sighting tube 83 is provided with a transparent member it in the form of a disc having cross-hairs (not shown) thereon. The cross-hairs may be adjusted to an meridional position by loosening the binding screws it and rotating the cap member t9 and the point of intersection thereof is coaxial with the tube and provides means with which a marked center on the blank may be aligned by sighting through the openings H and 72. This accurately centers the lens blank.

The assemblage including the body member 55, contact members 5!, spring fingers 63, and their cooperative parts, is slidably supported in the housing 58 and is constantly urged by gravity toward the lens supporting table 8. A rack supporting lug T3 is bolted or otherwise secured to the body member at a point well below the lower end of the housing 53 and has connected thereto by screws 55 the lower end of a vertically extending toothed. rack is, the rack being slidably disposed through an opening in a boss 8i! formed integral with the rear of the housing 53. A pinion gear 8! adapted to mesh with the rack 79 is fixedly secured to a shaft 82, the shaft being rotatably mounted in the bracket 6 and having an operating knob 83 (Fig. 1) secured to one end thereof. Thus, manual rotation of the knob 33 will cause vertical movement of the body member 55 and consequently of the contact members 5i and spring fingers 63, toward or away from the lens blank 50.

Means may be provided for holding the sighting device in its raised position. Such a device is illustrated in Fig. 8 and includes a coil spring 86 which is located in a transverse bore 85 in the supporting bracket 6 and is adapted to urge a ball member 86 positioned adjacent its outer end toward the rack 19. The bore 85 is threaded near its outer end for reception of a threaded stud 81, which stud serves to retain the spring within the bore 85. A small cavity or indentation 83 (Fig. 2) is formed in the side wall of the rack 79 where it may be engaged by the ball member 86 of the spring detent when the sighting device is in its raised position. When the ball member 86 engages the cavity 88 the action of the coil spring 84 will maintain the sighting device in its raised position. The sighting device may, however, be lowered by rotating the knob 83 to overcome the force exerted by the spring 84.

In using this portion of the subject invention, the handle 6% is initially moved to spread the spring fingers 53 outwardly. The knob 83 is then manually rotated to lower the sleeve 5'5, and the contact members 5| are guided into engagement with the upper surface of the lens blank 5!! positioned on the pin members 48. The said blank has been previously aligned as to center, its prism and cylinder axes, and the extent of prism, and during the locating of the contact members 5! said blank is preferably manually supported in desired aligned position on the pin members 43. The spring fingers 63 are now operated so that they will grip the contour edge of the lens blank 50. This is accomplished by moving the handle 66 to permit the spring fin ers to resiliently engage the edge of the lens blank with the contact members 5| engaging the upper surface of the blank. A check is then made by sighting through the sighting tube 68 to insure that the lens blank has not moved from its desired prelocated position. The clamp screws 62 are then tightened to simultaneously secure the spring fingers 53 in gripping relation with the edge of the lens blank 50 and to secure the contact members 5! against longitudinal movement. It is to be noted that the gripping ends 65 of the fingers 53 are angled inwardly so as to insure a positive grip with the edge of the lens blank. After positively locating the spring fingers 63 and contact members 5! by tightening the clamp screws E2 the knob 83 may be again rotated to raise the body member 55 and consequently lift the lens blank 56 off the pins After removing the lens 50 from the pin members 46 the machine operator will rotate the handle 24 to raise the table 8, as hereinbefore described, and by grasping the short extension 21 will swing the table on the axis of the vertical shaft [5 to a sidewise position substantially as shown in Fig. 3.

Located by bolts 89 on the base i in axial alignment with the sighting device is an upright which has a tapering support 90 thereon on which is fitted an adapter 9| holding a lens block 92. The upright is formed with a base portion 93 on which resides a ring member 94 which is adapted to rotate about the tapered support 96. A vertical locating pin 95 is fixedly positioned in the upper surface of the ring member 94 and is adapted to accident engage aslot 96 in the adapter '91. Thus by rotate. ing; the: ring memben t t and pintfil' the-adapter 9|: may be'locat'ed as desiredg setascrews- Slibeing provided to lock the ring member'94iin' adjusted position. The adapter-9i has a recessed upper end. (Fig. 7 inwhich is:extended 'a shank. 98 on the under: side of the block 92; the: shank 93 having a. circumferential taper: 8 9 which is adapted to be engaged by a plurality of set screws." Hail; The tapered portion 9i; issuch-that the binding action of the set screws new moves the=blocle 92 in'a direction: inwardly. of therecess. The adapter 9| also has a tapered recess in itslower surface whereby it may be easily positioned onthe tapered portion Hil'of the upright in axialali'gnment with the disc member 28 and" sighting device: It" is to be understood that the upright may be: pere manentlyattached to the machine and i'sprovided with a central opening axially aligned with the sighting tube 68 and openings 3%- and- 3b in the base I5 and table 8 respectively; the ad'apter M to be attached after removal of the-table 8 from position directly above theupright'.

The lens block 92 car-ries ail-adhesive which-has been'previously affixed thereto, the adhesive being preferably in the form of" a solid pellet Hil (Figs: 12 and 13) of pitch or the like, and-*isused for securing the lens blank to the: lens block. Thepellet liil may bemade of any of'the-commonly known heat-effective adhesive compositionsused forthis-purposeandis preferably ofa substantial disc shape, the composition being molded or otherwise madeinto solid form with a backing m2 of c'rinolineor other suitabl'e coarse, foraminous reinforcing material pressed into-the pellet during the initial fabrication thereof and while the pellet is" a soft orpliable condition. Since pellets of this type are thin. and may become broken during initial handling or whenplaceol' on the-lens holder or block the backing provides means forretaining; the broken pieces together" and also serves to-retardsidewise-flow of the adhesivaunder'the action of heat; Also, the fabric backingl'll2 will enablethe lens blank tobe much more easily removed eventually from alens block;

In applying the adhesive pell'et tilt to alens block means such asafurnace i 03- (Fi'gs; l band 15) is employed, whiclrfurnaceniaybe of any suitable type embodying a housing: ted having walls made of suitable heat resistant material and having ashelf iii-5 located therein. tray i99 having a plurality of openings therein? is adapted'to carry asupply of lensblocke $2 each: block having: an adhesive pellet:- let: disposed on. its upper surface; The tray tee': carrying the supply of blocks 92 and pellets" it'll is adapted to be placedinside the housing ition theshelf 5-135 a: door it? being suitably hinged te -the: housing:

to provide easy access intothe" interior thereof:

A source of heat such as: coils use: are located Within the housing Mi l and are adapted; whenenergized, to radiate heat onto the surfaces of the lensblocks 92- on the tray use and cause the pellets carried by the blocks e2 to become at least partially molten. After heating, the blocks and pellets are'permitted to cool to secure the pelletefirmly to the blocks whereupon the blocks maybe'reznoved from-the tray andused in block: ing devices.

Since it is possible to burn the adhesive and thereby render the pellets useless for present purposes it is desirable to provide means for automati'cally timing the heating cycle and thereby permit the pellets to be satisfactorily attached tothe blocks. This is accomplished through the use of an.-.e1ectrical1 timing: device use provided adjacent the furnace 103 and:inthe electrical circuit to the heating elements lfiEe Ailterinserting. the tray I06 carryingthe supply of blocks es and pellets Iii-l: in the; furnace the electrical circuit to the coils: I68 Willbe energized. and: the timing. device I this will= then; operate: to break the circuitto thecoil's;after a; predetermined; length oftime has: elapsed. Thisiprovidesasiinple fast andefiicient method of applying adhesive: pellets to lens. blocks in substantially; large quantities.-

After the table 8: has beenremovcdgfrom posi:-. tionover. thesupports 2' and 3: as described an adapter. 5 I carrying av block $12: with. an. adhesive; pellet lee. securely affixed thereto. is. placed% on the tapered: portion ail of" the :upright .and' means is .then. employed: for. securing; the, lens 5a. to the block 92'. Such. means: includes a. heating ele-. ment' km which is rotatablymounted ion insertion between the lens 5.3 and the block 92;

A. vertical opening in the-rear portion. of: the

support carries: ashaft I If (Fig; 4;) which'icara ries the heating element I 1.0 adjacent its upper. end", the: opening beingofrsuchlsiae as-to rotatably receive theshaft Mil; andghavi'ngani aligned opens, ing of: smaller; diameter extending from. the lumen end thereof adapted tnreceive an: extension 522 on the lowenendi of. theashafti Hit]; The eaten, sion: I-irZ; of" the shaft- Hill has. secured: thereto. by. a pinion othersuitabl'e meansa collar- HF? carry-l inga; pair of. eccentnicallyalocatecl studs; I Mi and: i-i'ntha siui'cls:- l tit and? me. being adapted:- to'; en. gage leaf springsil wand lr'h'l whiehianeconnected tolandi act": as; the respective: actuating members frapair ofrmicroeswitchesi a: and H29, which switches are securedi to-thebase IL means such as scnews: I20; and:- are adapted tobecontacted'. by the studs l-Ht and M5 to open-and close the switches H8 and I i-=9 upon rotation of the shaft Mt.

Terminals: new are provided in the non-com ducti-vebracket: portion I 2r 0f the heating element Hil (Fig. 3 and have the coils I22 off theheating element connected thereto: The heating element is also connectedby-suitable i213} into the" circuit illustratedin Fig; 16. I

A knob I 24 carried by a handle I25 is adapted to be grasped by the 1 operator to rotate the heat ing element Mil fromits normalunheated position withinacavityor depression [26 formedin the upright 4, I asshown byd'otted out-linein Fig; 3; tp thciQosltion shown by-solid lines in the same illustration; whereby the heating element Willi be disposed betweenthe lens. blanglg 5E)" and the ens lock, 9 as; hown E 21 otation; it e h atin element; Lit. and n queniily of; he-s aft I llwi cause th in. us. l censees. eaf sprin Us. to; e te he: mind-sw t h i s; whi h. en rg zes the 2.0. 1. 13; in the eating lieme t. 110.

R ferring. to th Wirin diagram. (Fig, 1.61) he standy ondi ion o the cir uit, t the main; switch; t c s d. p rmits cement to: pass f m. he. sour o current SE. hllQ gh lead. tothe I filament. 1.238. of: a. dual purpose rectifier amplifier;

h rm nievawummu asthma. 0f

the ther le tri al: parts. masbe lecati d circuit being completed through lead e to the source of current SC.

When the heating element is swung out and micro-switch IIS operated, this will energize the heater coils I22 through circuit c-bjg-e. This will simultaneously break the circuit to the rectifier filament I3I, preventing current from passing to the condenser I 33, whereupon the charge on condenser I33 will commence to drain off through resistors I34 and I35. Heretofore, the filament I28 of the tube has not been permitted to pass current since it is biased by the charge on the condenser I33. However, after a predetermined length of time, which time has been computed so as to permit the coils I22 to heat the adjacent surface of the lens blank 53 and the pellet I05, the condenser charge will reach a point low enough to allow enough current to pass from the filament I28 to the plate I 36 to energize the relay I 3 5, circuit ah7'k m-e. Relay I3! upon being energized will close to complete the circuit to a latching solenoid 233, circuit a-h--n-p-e.

When the heating element III] is initially moved into operative position a latch I 39 is adapted to engage a notch formed in the rear of the non-conductive bracket portion IZI of the heating element III], the latch I39 being secured to the armature I46 of the solenoid I38 and constantly urged toward the heating element I!!! by a coil spring I 4|. When the solenoid I33 is energized by the closing of relay I31, however, it will cause the latch I 39 to be drawn rearwardly by the armature I40 against the tension of the spring l4l, and the heating element III! will then be free to return to its inoperative position in the space I26 within the upright 4. The return movement of the heating element III! is under the influence of a coiled tension spring I42 which is located over the rotatable shaft I42 and is suitably connected thereto in such a manner that upon release of the latch I39 the spring I42 will immediately return the heating element to the position indicated in dotted outline in Fig. 3.

When the heating element returns to its inoperative position the rotation of the shaft II I will return the microswitch IIB to its normal initial condition, thus breaking the circuit to the heater coils I22 and restoring the bias voltage through the filament ISI and plate I32 of the tube I29. With the bias voltage thus restored the passage of current to plate I36 is interrupted. Relay I31, which would ordinarily open immediately, is then momentarily prevented from opening by the charge on a condenser I43, which condenser stored energy when the relay was energized. However, when the condenser I43 has been drained sufficiently the relay I3'I will open. This slight delay is sufficient to permit the heating element H to return to its position within the upright 4 whereupon the shaft III will be rotated sufiiciently to cause pin H to engage the leaf spring II'I, thus closing micro-switch I20, allowing current to pass to a dropping solenoid I44, circuit a-h-n-q-r-e.

The dropping solenoid I44 is located on a bracket I45 secured to the top of the sighting device housing 58 (Fig. 2) adjacent the upper end of the rack 19. When the solenoid I44 is thus energized, the armature I46 therein will be quickly moved downwardly and will forcefully engage the end of the rack"!!! and overcome the force exerted by the spring detent device (Fig. 8) and the sighting device carrying the lens i2 blank 50 will drop downwardly to bring the heated lower surface of the lens blank 50 into pressing intimate engagement with the heat softened adhesive pellet II.

It is to be understood, therefore, that the opening of relay I31 must be delayed for a time sufiicient to permit the heating element to retract and cause energization of solenoid I44. Then upon the draining of the condenser I43 and consequent opening of relay I31, this will break the circuits to both solenoids I38 and I44 and thus return the entire circuit to its normal standby condition.

The timing. cycle for the heating operation can be varied by manual adjustment of the variable resistance I35 to control the drain on condenser I33. The lamp 33 is also included in the circuit and arranged so that it will be illuminated when the main switch I21 is closed, circuit a-s-t-e.

A lens blank 50 when in lowered position is constantly urged toward the pitch pellet IBI as described hereinbefore so that shrinkage due to the cooling of the pellet is compensated for. When the pellet has cooled sufiiciently to secure the lens blank 50 to the block 92, the clamp screws 62 are loosened, whereupon the spring fingers 63 may be moved outwardly through manual operation of the handle 66. The fingers 53 and contact members 5I, body member 55, and associated mechanism are then lifted in the housing 58 by manual operation of knob 83, and the adapter 9| together with the lens block 92 having the lens blank 53 secured thereto may be lifted off the upright 90.

When the sighting device carrying the lens 51'! is caused to drop to locate the lens blank upon the block 92, the dropping movement is under the control of a suitable motion dampening device such as the dashpot I 41 (Fig. 2) which constitues a cylinder I48 located upon the web 5 of the upright 4 and filled with a liquid I49 of the desired viscosity and having a plunger I50 connected by a connecting member I5I to the rack I9 and adapted to move therewith. Thus the speed at which the lens blank 56 is brought into engagement with the pellet I0! is controlled and possible breakage prevented.

The upright for supporting the lens block adapter 87 is provided with a vertical opening I52 (Fig. 2) axially aligned with the base opening 32 and table opening 3| to permit illumination from lamp 33 to pass upwardly through the translucent light diffusing member 38 and to illuminate the lens blank 58. The lamp 33 is controlled by the switch I27 and may be positioned slightly out of alignment with the opening 32 and the member 36 for the purpose of providing indirect diffused light or may be directly in alignment therewith in order to provide the greatest illumination on the lens blank 50. If desired, suitable means may be provided for moving the lamp 33' into and out of alignment.

It is to be understood that the movable lens supporting table 8 may be provided with simple adjustable means for aligning the bushings It in the under side thereof with the pins I2 when returning the table 8 to its position in spanning relation to the supports 2 and 3 after a lens has been blocked and removed from the adapter iii, whereby the table 8 may be more quickly and easily positioned in axial alignment with the holding device for successive lens aligning operations. This may be accomplished by providing means genome located in the rear edge of the; table member 3 and adjustably. positioned: so that when the table 8 is swung to a positionspannin'g. the sup-l ports 2: and. 3 it will. abutt'he front surface of. the upright It to position the table for proper disposition. thereof. upon. the locking pins i2i without unnecessary feeling. or groping? Also, if desired, the. mechanism for'raising and: lowering the lens supporting tablet may be provided with a. spring. detent device for restraining the table from undesired vertical movement. tent similar to the spring detent of" the sighting; device is illustrated: in.I ig-'..6=wherein acoil: spring infi i and ball member 1515. cooperate: with cavities or: indentations: i 55.: the. transverse shaft: t9;

the spring and. ball being positioned. in. a vertical bore 157- in. the base I and. retained therethe introduction of prism in a lensblank may be.

accomplished b using ball members its provided with integral pin extensions sof. varying lengths, the extensions adapted. to reside in vertical openings 15'! formed in the uppersurface of the disc member 28 The amounts of prism to be introduced in a lens blank can be easily varied by employing ball members I555 with extensions I55 of lengths controlled according to the prism desired. Additional openings (not shown) may be provided in the surface. of thev disc member 28 in which the ball members. may be located if desired, the openings being. spaced. radially of and equidistant from the axis of the disc member 28. The purpose of providing. such additional openings is to enable the blocking of. lenses which do not have a continuous surface thereon, such as, for example, biiocals wherein the segment portion of the bifocal isof a, different curvature than the adjacent surface of the blank. By placing the ball members G55.- in the proper openings all of said members. may be made to engage the surface of the.- blank adjacent to and at a location clear of the segment portion.

It. is also to be understood that the table. 8 may:

bore adapted to fit over the tapered upright 86 for positional purposes and. may be used either with or without the contact members 9 and Ill.

From the foregoing descriptionit will be. seen. that an invention of the character described; is very definitely an improvement over the prior art by providing a machine with improved means for sighting and gripping semi-finished lens blanks for introducing desired optical character-- istics which the finished lens is. to possess, and; the lens blank held by the improved gripping means in such a manner as to retain. its position with respect to the prescriptive characteristics; also by providing: means for preliminarily attaching a quantity of adhesive pellets to an equal number of blocks before the lens blocking operation; and also. by providingv neat. and: ef ficient means for securing. a lens. blankto a lens block by including a heating element movable under automatic. electronic control and adapted to heat the adjacent surfaces of the lens. blank and the adhesive pellet to join. the. lens blank to: the block. in a very satisfactory manner, in

Such. a deii4 contrasts to: the: messy; means: employed by; prior art: devices which. are; generally of; as somewhat involved nature and: which employ apot can.

rying. a: molten adhesive and. accessories neces saryrto. confine; thepitch tocertain areas of the:

and; lowering. the lens blank in a vertical lineofi movementprependicularto the surface-of the; table: usedfor-initially supporting the lens blank and: by shortening. the; length of travel and con-- fining: the movement; thereof during the block ing; operation to said vertical linethereby eliminating toiagreat degree; possible inaccuracies in: bluckina.

The: advantages of: our; invention will be readily understood from; the foregoing description and;

While} we have. shown and. described a preferred.

embodiment; of our invention, it is evident, that various modifications'may be made that will come within: the scope: of; the invention, and We do; not desire; therefore, to. limit ourselves to the exact form of constructionshown and; described herein.

Having; described our invention, we claim:-

1 Inv adevice of the character described, the combination of a base, adjusting meansv on said base for supporting a lens blank in. a predetermined. position, a holding device supported on said basehaving gripping means adapted to contactand. retain. said lens blank in adjustedpositicn, said= holding device being movable withsaid-i gripping. means and said, lens blank in a direction toward 01" away from the adjusting means, retaining means on said basenormally supporting said holding device; in a position, spaced from the; adjusting. means, lens block supporting means onsaid base having a lens block supported there-= on. in spaced axial alignment with said holding device, said; lens block having a. heat scftenable adhesive substance fixedly secured. to the surface thereof, a heating. device rotatably mountedon said; base and adapted to be moved into and out ;of=. operative position between the lens blank .tatio-nthereof intooperative position betweenthe blank and adhesive, a timing device. under control of said switch and means operable by said timing; device for automatically returning the heating element to. inoperative position from between the blank and adhesive upon completion of the. timing cycle, and a second switch. arrangement. operable by the heating elemcntu-pon rotation into. said. inoperative position from be tween thev blank. and adhesive and means ens ergizableby said. second switch releasing said. retaining. means and moving the holding devise for. the lens blank toward the lens block so that the. lens; blank will engage; with the adhesive on the-lensblock while. the lens blank is retained adjusted position.

2. Ina device of the character described, the combination of a base, adjusting means located onsaid base comprising a table member provided with a member carrying adjustable spaced. contacts on which. a: lens blank is adapted to reside, said member-beingadjustable to locate the: lens blank. in accordance with its. predetermined cylinder axis, said contacts being adjustableto provide angular displacement of the lens blank to: introduce a predetermined amount of prism thereto, a. holding device. supportedon. said. base in axial alignment. with; saidv adjusting.

means and movable in a direction perpendicular to the surface of said table member, said holding device having gripping means adapted to contact the peripheral edge of and retain said lens blank in adjusted position, said holding device being movable with said gripping means and said lens blank in a direction vertically toward or away from the adjusting means, lens block supporting means on said base in spaced axial alignment with said holding device and adapted to support a lens block having an adhesive affixed to the supporting surface thereof, a heating device mounted on said base and adapted to be moved into and out of operative position between the lens blank and the adhesive on the lens block to heat the adjacent surfaces thereof, means effecting the return of the heating element to inoperative position from between the blank and adhesive, latch means resisting said return effecting means to retain the heating element in operative position, control means operable by movement of the heating element into operative position for unlatching said latch means at the end of the heating cycle, and means operable by the heating element upon return to said inoperative position for effecting the engagement of the lens blank with the adhesive on the lens block to secure the lens blank to the lens block while the lens blank is retained in adjusted position.

3. In a device of the character described, the combination of a base having spaced supports thereon, adjusting means located on said supports comprising a table member rotatably mounted on said supports and normally positioned in spannin relation thereto, said table member having a rotatable disc member located thereon carrying a plurality of individually adjustable spaced contacts on which a lens blank is adapted to reside, said disc member being adjustable to locate the lens blank in accordance with its predetermined cylinder axis, said contacts being adjustable to provide angular displacement of the lens blank to introduce a predetermined amount of prism thereto, controlling mechanism for positioning said table member comprising a plurality of pin members located in said supports and adapted to comate with openings in said table member, and manually operable lifting means associated with said table to raise it from said pin members to permit the table to be moved, a holding device supported on said base in axial alignment with said adjusting means and movable in a direction perpendicular to the surface of said table member,

said holding device having gripping means adapted to contact and retain said lens blank in adjusted position and being movable with said gripping means and said lens blank in a direction vertically toward or away from the adjusting means, lens block supporting means on said base in axial alignment with said holding device and adapted to support a lens block having an adhesi ve afiixed to the supporting surface thereof, a heating device mounted on said base and adapted to be moved into operative position between the lens blank and the adhesive on the lens block and to heat the adjacent surfaces thereof, electronic means controlling the heating cycle and effecting the return of the heating element to inoperative position from between the blank and adhesive at the end of the heating cycle, and means operable by the heating element upon return to said inoperative position for effecting the engagement of the lens blank with the adhesive on the lens block to secure the lens blank to the lens block while the lens blank is retained in adjusted position.

4. A lens blocking device of the character de scribed having adjusting means for locating a lens blank in a predetermined positional relation, a lens blank holder for releasably supporting the blank in said adjusted relation, 3, lens block holder for supporting a lens block with adhesive on a surface thereof in axial alignment with the lens blank holder, one of said holders being movable toward and away from the other holder, restraining means normally retaining said movable holder in spaced relation to the other holder against a force urging said holder to move toward the other holder, a heating member mounted for movement into and out of an operative position located between the holders for heating said adhesive on the surface of the lens block, and switch means operated by movement of the heating member out of said operative position and causing when so operated the resistance of the restraining means to be overcome whereby the lens blank and the adhesive on the surface of the lens block carried by the respective holder may be automatically brought together so that the lens blank will be secured to the lens block and while retained in its adjusted relation.

5. A lens blocking device of the character described having adjusting means for locating a lens blank in a predetermined positional relation, a lens blank holder for releasably supporting the blank in said adjusted relation, a lens block holder for supporting a lens block with a coating of adhesive on a surface thereof in axial alignment with the lens blank hoider, one of said holders being movable toward and away from the other holder, latch means normally retaining said movable holder in spaced relation to the other holder against a force urging said holder to move toward the other holder, a heating member supported for movement into and out of an operative position between the holders for heating said adhesive coated surface of the lens block, switch means operated by movement of the heating member out of said operative position and causing when so operated the resistance of the latch means to be overcome whereby the lens blank and adhesively coated surface of the lens block carried by the respective holder may be automatically brought together so that the lens blank will be secured to the lens block and while retained in its adjusted relation, and cushioning means controlling the speed of movement of the movable holder toward the other holder.'

6. A lens blocking device of the character described comprising a lens blank holder for releasably supporting the blank in a pro-adjusted positional relationship, a lens block holder for supporting a lens block with a coating of adhesive on a surface thereof in axial alignment with the lens blank holder, one of said holders being movable toward and away from the other holder, latch means normally retaining said movable holder in spaced relation to the other holder against a force urging said holder to move toward the other holder, a heating member supported for movement into and out of an operative position between the holders for heating said adhesive coated surface of the lens block, locking means holding the heating member in said operative position against a force urging it out of said. operative position, control means operated by movement of the heating element into said operative position to unlock the locking means at the elapse of a predetermined time interval and 1 7" switch aessrerei hi" ce ent 'iea me b'ei;siipp r ed formov men int and, utgo ve position between the holders ier-heatcontrol mechanism comprising a first latch normal r e ai in h mov e ho der t a sition spaced from the other holder against a force urging it toward the other holder, a secondlatch normally retaining the heating member in said operative position between the two holders against a force urgingsaid heating member to an inoperative position, a pair of solenoids operating said respective latches, said solenoids being located inrespective circuits for connection of the solenoids to a, source of electrical energy to energize the same, and a control switch in each of said circuits, one of said switches being operated by movement of the heating member to itsoperative position between the holders to permit energizing the solenoids actable upon the second latch when the adhesive coated surface of the lens block has been sufficiently heated by the heating member to automatically move the heating member out of said operative position between the holder and the other of said switches being operated by movement of the heating member to its inoperative position to energize the solenoid actable upon the first latch causing said latch to release the holder restrained thereby whereby the lens blank and adhesively coated surface of the lens block carried by the respec-- leasably supporting a, lens blank in a rare-adjusted V relation, a lens block holder for supporting a lens block with a coating of adhesive. on a surface thereof in axial alignment with the lens blank holder, oneof the holders being movable toward and away from the. other holder, and a heating member supported for movement into'and out of operative position between the holders for heating said adhesive coated surface ofthe-lensblock, control mechanism comprising a first latch normally retaining the movable holder spaced fr the other holder a a a forceurging it i the other holder} at secondlatch reta i'ningtl'i e heating member when positioned in said operative position between the two holders ag ainst a' force urging said heating memberout of said position; said latchesb'eing' operated byfa' pair of soleno ids,- a; pair or; circuits for connecting said: r q d to s ce .e gele c l ene g to k mitenerg'izingpfth'e same; and a circuit breaking switch 1ne'achof said circuitsto permit en ame or the respective solenoids, ne or serif;

e h -holder nd. aheatme,

sa dadhe'siv batedsfir 'e the l n 1QQk,- I v rki the izis it m ans act-able pon said heating device for perative posit on, s vitqri- We i ldfl fl means operated by vice cutter s d p s on.-

10. In a' eticdrth.cfiarec er described, the

ment with, the adh a'e'e 'oii l9 s when in adjusted position, retaining means nor-' mally supporting said holding device in a posi= tion spaced from the lens block supporting means against a force urging the holding device toward the lens block supporting means, a heating de-'- vice mounted on said base for movement into operative position between the holding device and supporting means to heat the adjacent surfaces of the lens blank and the adhesive on the lens block when supported by the respective supporting means and holding device, means acting upon said heating device for moving it out of said operative position at the completion of the heating cycle, switch means operated by said movement of the heating device out of operative position and said switch means'when so operated acting on means causing said retaining means to cease its support of the holding device and permit said force to move the holding device to the lens block supporting means whereby the lens blank may be secured to the adhesively-coated surface of the lens block while'retaining its adjusted position.

11. In a device of the character described, the combination of a base, supporting means located on said base for supporting a lens block having an exposed adhesive coated surface thereon, adjusting means on said base for adjusting a lens blank to a predetermined position relative to said block, and lens blank holding means supported on said base in axial alignment with said lens block supporting means and slidably mounted for movement in directions toward and away from the lens block supporting means, retaining means normally upporting said lens blank holding means in a position spaced from the lens blocksupporting means against a force urging it toward the lens block supporting means, a heating device mounted on said base for movement into operative position between the lens blank holding means and lens block supporting means to heat the adjacent surfaces of the lens blank and the adhesive coated surface of the lens block when supported by said respective means, switch means operated by movement of the heating device out of said operative position, and control means energized by the operation of said switch means causing said retaining means to cease its hold on the lens blank supporting means whereby the lens blank may be brought into engagement with the adhesive coated surface of the lens block while retaining its initial adjusted position, and cushioning means dampening the movement of said lens blank holding means toward the lens block supporting means.

12. In a device of the character described, the combination of a base, adjustment means located on said base for adjusting a lens blank to a, predetermined position, a holding device supported on said base in axial alignment with said adjusting means and being moveable toward and away from said adjustment means, gripping means carried by said holding device to contact the peripheral edge of said lens blank and retain it whenin adjusted position for movement with the holding device, lens block supporting means on said base, resilient retaining means carried by said base and normally frictionally engaging said holding device so as to retain it in a position spaced from the lens block supporting movement against a force normally ur ing the holding device in a direction toward the lens block supporting means, a heating device mounted on said base for movement into operative position between the holding, device and lens'block supportingmeans to heat the adja- 20 l cent surfaces of the lens blank and an adhesive coated lens block when supported thereby, switch means operated by movement of the heating device to inoperative position, and means responsive to operation of the switch causing the said force acting on the holding device to overcome the frictional force of said retaining means and move the holding device and lens blank carried thereby into engagement with said adhesive coated lens block to permit the lens blank to be secured to the lens block while retaining its adjusted position.

13. In apparatus of the character, described the combination of a lens block having a lens blank receiving surface, adhesive means disposed.

on said surface, heating means positioned for softening said adhesive to a condition where it will adhere to said surface of the lens block, a holding device supported in axial alignment with said surface of the lens block and for movement in directions toward and away from said surface of the lens block, adjustment means moveable into and out of position between the lens block and said holding device for supporting a lens blank for adjustment, said holding device having gripping means for releasably engaging said blank and supporting it during movement of the holding device toward and away from the lens block, retaining means frictionally engaging said holding device to restrain it against movement under the action of a force urging it toward the lens block, and a heating element supported for movement into operative position between the lens blank holding device and the adhesive means on the surface of the lens block to heat the adjacent surfaces of said lens blank when carried by the holding device and the adhesive means on the surface of the lens block, switch means operated by movement of said heating element out of said operative position, and means responsive to operation of said switch means causing said holding device to overcome the frictional force of said retaining means and carry said lens blank when so supported by the holding device into engagement with said adhesive means on the surface of the lens block, whereby the lens blank may be secured to the lens block while retaining its adjusted position.

14. An attachment for use with a lens blocking machine of the type embodying a vertically moveable lens blank holding device having gripping means for' contacting and releasably retaining a lens blank in a preadjusted position, a lens block positioned adjacent to and in axial alignment with the holding device and carrying a heat softenable adhesive, and a heating element moveable into and out of operative position between the lens blank and the lens block, said attachment comprising spring means to'be operatively assembled with the heating element for normally urging said heating element into inoperative position, a latch to be operatively assembled with said heating element for retaining the heating element in said operative position against the force of said spring means, an electrical circuit for use in connecting said heating element to a source of current, a switch in said circuit normally maintaining said circuit open and operated by movement of the heating ergize the heating element when the attachment is in use, a control device in said circuit-and simultaneously energized by operation of saidswitch, said control device when so energized being operatively connected with the latch for causing said latch to release the heating element at the end of a predetermined time interval so that it will return to inoperative position from between the blank and adhesive, restraining means for normally retaining said holding de" vice at a position spaced from the lens block supporting nieans against a force urging it to move to the lens block when the attachment is in use, and solenoid operated mechanism adapted to be responsive to the movement of the heating element to inoperative position when the at tachment is in use causing said holding device to overcome the resistance of the restraining means to permit the lens blank to be moved into engagement with the adhesive on the lens block.

15. In a lens blocking machine of the type embodying a vertically moveable lens blank holding device having gripping means for contacting and retaining a lens blank in a preadiusted position, a lens block positioned adjacent to and in axial alignment with the lens blank and carrying a heat softenable adhesive and a heating device movable into and out of operative position between the lens blank and the lens block, the combination of resilient means assembled with said heating device for normally urging it into an inoperative position, latch means operatively associated with said heating device for retaining said heating device in its operative position between the lens blank and the lens block against the urging of said resilient means when moved into said operative position, an electrical circuit by which said heating device is connected to a source of current, a switch in said circuit and positioned to be ated upon by the heating device when moved into said operative position to permit energizing of the heating device by said circuit, a timing device responsive to the operation of said switch and having means associated with said latch means to cause it to release the heating device at the end of a Predetermined timing cycle, restraining means assembled with said holding device for retaining it against a force urging it to move toward the lens block, and means positioned to be responsive to the movement of said heating device to said inoperative position acting upon said restraining means to release the lens blank holding device whereby said lens blank will be automatically carried by the holding device into engagement with the adhesive on the lens block when the heating device has been moved to inoperative position to secure the lens blank to the lens block with the lens blank being retained in its preadiusted position.

22 16. In a'lens blocking machine of the type embodying a vertically moveable lens blank holding device having gripping means for contacting and releasably retaining a lens blank in a preadjusted position, a lens block positioned adjacent to and in axial alignment with the holding device and carrying a heat softenable adhesive, and a heating element moveable into and out of operative position between the lens blank and the lens block, the combination of spring means operatively assembled with the heating element for normally urging said heating element into inoperative position, a latch operatively assembled with said heating element for retaining the heating element in said operative position against the force of said spring means, an electrical circuit by which said heating element is connected to a source of current, a switch in said circuit normally maintaining said circuit open and positioned to be operated by the heating element when moved into operative position between the blank and adhesive to close the circuit and energize the heating element, a control device in said circuit and simultaneously energized by operation of said switch, said control device when so energized being operatively connected with the latch for causing said latch to release the heating element at the end of a predetermined time interval so that it will return to inoperative position from between the blank and adhesive, restraining means for normally retaining said holding device at a position spaced from the lens block supporting means against a force urging it to move to the lens block, and solenoid operated mechanism so positioned as to be responsive to the movement of the heating element to inoperative position causing said holding device to overcome the resistance of the restraining means to permit the lens blank to be moved into engagement with the adhesive on the lens block.

DANIEL P. BERNHEIM.

CARL G. SILVERBERG.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 537,014 Burton Apr. 9, 1893 2,031,380 Mo Cabe Feb. 18, 1936 2,191,952 Blau Feb. 27, 1940 2,286,212 Corn June 16, 1942 2,342,725 Crepau Feb. 29, 1944 2,463,669 Wright Mar. 8, 1949 

